Vehicle remote control electronic keys have been known for several years. In a known manner, certain keys possess a listening mode in which a key is able to receive information transmitted by a vehicle, by Ultra High Frequency (UHF) or Low Frequency (LF) link. The information indicates for example that a door of the vehicle has been forced, that a tire has burst, or that a window pane has been broken. When an item of information is received by the key, the key can signal same for example by emitting a noise.
Moreover, some of these keys are also able to transmit the information from the vehicle to a master entity of smartphone, PDA, or laptop computer type. Communication between the key and the master entity is conventionally performed by bluetooth protocol, by bluetooth low energy protocol, or by NFC protocol.
Conventionally, a vehicle key having a bluetooth or bluetooth low energy component, and able to communicate with a master entity, is able to take three states:                idle, in which the key neither receives nor emits signals, and is not connected to any other entity;        discoverable, in which the key periodically emits presence messages;        connected, in which the key is connected to the master entity.        
To exchange information, the key must be in the connected state. Prior to connection, the key must have been initially pinpointed by the master entity via the presence signals emitted in the discoverable state. Thus, to be able to communicate with the smartphone, the discoverable and connected states are invoked often, since the key must remain in the discoverable or connected state when the user needs it.
Now, the discoverable state, the connected state and the listening mode consume energy, thereby considerably reducing the lifetime of the battery of the key.